iommu/of: Refactor of_iommu_configure() for error handling

In preparation for some upcoming cleverness, rework the control flow in
of_iommu_configure() to minimise duplication and improve the propogation
of errors. It's also as good a time as any to switch over from the
now-just-a-compatibility-wrapper of_iommu_get_ops() to using the generic
IOMMU instance interface directly.

Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

1 files changed, 53 insertions, 30 deletions

diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
index 2683e9fc0dcf..8f4e59985f6e 100644
--- a/drivers/iommu/of_iommu.c
+++ b/drivers/iommu/of_iommu.c
@@ -96,6 +96,28 @@ int of_get_dma_window(struct device_node *dn, const char *prefix, int index,
 }
 EXPORT_SYMBOL_GPL(of_get_dma_window);
 
+static const struct iommu_ops
+*of_iommu_xlate(struct device *dev, struct of_phandle_args *iommu_spec)
+{
+        const struct iommu_ops *ops;
+        struct fwnode_handle *fwnode = &iommu_spec->np->fwnode;
+        int err;
+
+        ops = iommu_ops_from_fwnode(fwnode);
+        if (!ops || !ops->of_xlate)
+                return NULL;
+
+        err = iommu_fwspec_init(dev, &iommu_spec->np->fwnode, ops);
+        if (err)
+                return ERR_PTR(err);
+
+        err = ops->of_xlate(dev, iommu_spec);
+        if (err)
+                return ERR_PTR(err);
+
+        return ops;
+}
+
 static int __get_pci_rid(struct pci_dev *pdev, u16 alias, void *data)
 {
         struct of_phandle_args *iommu_spec = data;
@@ -105,10 +127,11 @@ static int __get_pci_rid(struct pci_dev *pdev, u16 alias, void *data)
 }
 
 static const struct iommu_ops
-*of_pci_iommu_configure(struct pci_dev *pdev, struct device_node *bridge_np)
+*of_pci_iommu_init(struct pci_dev *pdev, struct device_node *bridge_np)
 {
         const struct iommu_ops *ops;
         struct of_phandle_args iommu_spec;
+        int err;
 
         /*
          * Start by tracing the RID alias down the PCI topology as
@@ -123,56 +146,56 @@ static const struct iommu_ops
          * bus into the system beyond, and which IOMMU it ends up at.
          */
         iommu_spec.np = NULL;
-        if (of_pci_map_rid(bridge_np, iommu_spec.args[0], "iommu-map",
-                           "iommu-map-mask", &iommu_spec.np, iommu_spec.args))
-                return NULL;
+        err = of_pci_map_rid(bridge_np, iommu_spec.args[0], "iommu-map",
+                             "iommu-map-mask", &iommu_spec.np,
+                             iommu_spec.args);
+        if (err)
+                return err == -ENODEV ? NULL : ERR_PTR(err);
 
-        ops = iommu_ops_from_fwnode(&iommu_spec.np->fwnode);
-        if (!ops || !ops->of_xlate ||
-            iommu_fwspec_init(&pdev->dev, &iommu_spec.np->fwnode, ops) ||
-            ops->of_xlate(&pdev->dev, &iommu_spec))
-                ops = NULL;
+        ops = of_iommu_xlate(&pdev->dev, &iommu_spec);
 
         of_node_put(iommu_spec.np);
         return ops;
 }
 
-const struct iommu_ops *of_iommu_configure(struct device *dev,
-                                           struct device_node *master_np)
+static const struct iommu_ops
+*of_platform_iommu_init(struct device *dev, struct device_node *np)
 {
         struct of_phandle_args iommu_spec;
-        struct device_node *np;
         const struct iommu_ops *ops = NULL;
         int idx = 0;
 
-        if (dev_is_pci(dev))
-                return of_pci_iommu_configure(to_pci_dev(dev), master_np);
-
         /*
          * We don't currently walk up the tree looking for a parent IOMMU.
          * See the `Notes:' section of
          * Documentation/devicetree/bindings/iommu/iommu.txt
          */
-        while (!of_parse_phandle_with_args(master_np, "iommus",
-                                           "#iommu-cells", idx,
-                                           &iommu_spec)) {
-                np = iommu_spec.np;
-                ops = iommu_ops_from_fwnode(&np->fwnode);
-
-                if (!ops || !ops->of_xlate ||
-                    iommu_fwspec_init(dev, &np->fwnode, ops) ||
-                    ops->of_xlate(dev, &iommu_spec))
-                        goto err_put_node;
-
-                of_node_put(np);
+        while (!of_parse_phandle_with_args(np, "iommus", "#iommu-cells",
+                                           idx, &iommu_spec)) {
+                ops = of_iommu_xlate(dev, &iommu_spec);
+                of_node_put(iommu_spec.np);
                 idx++;
+                if (IS_ERR_OR_NULL(ops))
+                        break;
         }
 
         return ops;
+}
+
+const struct iommu_ops *of_iommu_configure(struct device *dev,
+                                           struct device_node *master_np)
+{
+        const struct iommu_ops *ops;
+
+        if (!master_np)
+                return NULL;
+
+        if (dev_is_pci(dev))
+                ops = of_pci_iommu_init(to_pci_dev(dev), master_np);
+        else
+                ops = of_platform_iommu_init(dev, master_np);
 
-err_put_node:
-        of_node_put(np);
-        return NULL;
+        return IS_ERR(ops) ? NULL : ops;
 }
 
 static int __init of_iommu_init(void)